Non-Patent Literature 1 discloses a power module. In the power module, one main surface (underside) of a power device (semiconductor chip) is fixed to a heat spreader with solder while surface electrodes formed on another main surface (top surface) of the power device are directly fixed to the inner leads of a lead frame with solder.
FIG. 35 is a cross-sectional view schematically showing the structure of a power module 101 disclosed in Non-Patent Literature 1. In the power module 101, a surface electrode (not shown) formed on the top surface of a power device 102 is directly fixed to a main terminal 103 via a solder layer 104. Moreover, another surface electrode (not shown) formed on the top surface of the power device 102 is electrically and mechanically connected to a control terminal 105 via a wire (thin metallic wire) 106. The underside of the power device 102 is fixed to a heat spreader (metal block) 108 via a solder layer 107. The underside of the heat spreader 108 is fixed to a metal layer 110 via an insulating sheet 109 made of an insulating resin. The constituent elements of the power module 101 are molded with a mold resin 111. The main terminal 103 and the control terminal 105 partially protrude from the outside shape of the mold resin 111.
Patent Literature 1-discloses another power module. The power module includes an insulating substrate made of an insulating material such as ceramic between a semiconductor chip and a heat dissipating plate.
FIG. 36 is a cross-sectional view schematically illustrating the structure of a power module 201 disclosed in Patent Literature 1. In the power module 201, an electric conductor 203a is formed on one surface (top surface) of an insulating substrate 203. A semiconductor chip 202 is fixed to the surface of the electric conductor 203a via a solder layer 204. The insulating substrate 203 is made of an insulating material, e.g., ceramic. Another electric conductor 203b is formed on another surface (underside) of the insulating substrate 203. The surface of the electric conductor 203b is fixed via a solder layer 206 to a heat dissipating plate 205 disposed below the semiconductor chip 202.